Internally multiplies the rendered resolution by a given factor. Using value higher than 1 increases memory consumption significantly, but when used, it is possible to antialias very bright edges of lights. Use default value of 1 unless light edges antialiasing is needed, in that case set it to 2.See:I can see jagged edges!

Render Non-shading elements separatelyEach element in Corona Renderer, which is computed during rendering, consumes memory. More elements = more memory usage. This rule is especially significant while rendering high-resolution images.

Renders only render elements which are not dependent on the beauty pass. This process is almost instant. The antialiasing of the output can be turned on/off with the checkbox to the right.For a list of all available render elements, see:What render elements are there?

If you are using displacement, in Render Setup > Performance under "displacement"section set displacement's "screen size"toa higher value

Other possible causes of excessive RAM usage include rendering large amounts of objects or detailed mesh - in such case it is advised to optimize the scene.